1. Field of the Invention
The present invention relates to an exposure apparatus, an exposure method, and a method of manufacturing a device.
2. Description of the Related Art
To improve productivity, a conventional exposure apparatus measures the surface position of a wafer, mounted on a stage, while the stage moves. When the surface position of the wafer is measured while the stage moves and especially while the stage accelerates or decelerates, deformation of the main structure of the apparatus occurs, thus generating a measurement error in the measurement result of the surface position. An exposure apparatus disclosed in Japanese Patent Laid-Open No. 11-191522 obtains a correction value to correct for errors in measurement, prior to exposure. This correction value is calculated based on a pitching component of the stage orientation. The exposure apparatus corrects the measurement result of the surface position, measured while the stage moves, using the correction value, and exposes the wafer in accordance with the corrected surface position.
However, Japanese Patent Laid-Open No. 11-191522 discloses no technique for measuring the level of a substrate while the stage accelerates, positioning the stage which is moving at a constant velocity, based on the measured level, and exposing the substrate. To meet the recent demand for a further improvement in productivity, the acceleration value or the deceleration value of the stage is likely to increase so as to quickly position the stage. As a result, not only deformation of the main structure of the apparatus but also that of the stage itself and even that of a measurement device mounted on the stage, such as a reference mirror for a laser interferometer, occur, so the measurement result obtained by the measurement device includes a measurement error due to factors associated with acceleration of the stage.